The World of Us (2016) online

At an age when perhaps friends mean more than moms, 10 year-old Sun is an outcast at school. During summer vacation, she meets Jia, who is new to town. As Sun shows Jia around the neighborhood and they play at each other's houses and share secrets, they become best friends. However when the new semester starts, Jia notices a strange vibe between Sun and the other kids. Jia tries to get into the cool kids group and starts to distance herself from Sun. Inside the perhaps more complex and delicate world of children than adults, the two girls end up hurting and getting hurt by each other.